The invention is related to the field of data storage.
Techniques for data migration and for device encapsulation in data storage systems are generally known.
U.S. Pat. No. 7,809,912 of Bappe et al. describes methods and systems for minimizing disruptions when host data on a source logical storage unit is migrated to a target logical unit. I/O requests are managed in a particular order during various states of the migration. After the target logical unit is synchronized with the source logical unit and before a commitment to the target logical unit is made, the target logical unit can be evaluated. At that point, the migration can be aborted if necessary. During the evaluation of the target logical unit, I/O requests that were directed to the source logical unit are redirected to the target logical unit and I/O requests that were directed to the target logical unit are redirected to the source logical unit. The disclosed methods and systems can also be used for less-disruptive virtualization of a source logical unit as a target logical unit. One feature of the disclosed methods is that a user can control, using among other things a program running in user space and a filter driver, a migration through transitions between different stages or “states.” The program provides a user interface via which the user provides high-level commands such as “Setup”, Synchronize”, etc. as more particularly described in the '912 patent.
U.S. Pat. No. 8,332,613 of Glade et al. describes a particular use of the technique of the '912 patent for minimizing disruptions when host data on a physical volume is encapsulated into or de-encapsulated from a virtualization layer. One common use for encapsulation is to speed up the process of transitioning a storage volume into network virtualized storage by avoiding data copies. Other common reasons include avoiding the need for additional storage during a data migration process. The act of transitioning storage from array-based storage to network virtualized storage allows that storage to gain the benefits provided by network virtualized storage including inter-array replication, application transparent data mobility, and flexibility in the quality of service provided for a volume for example.
U.S. Pat. No. 7,904,681 of Bappe et al. describes methods and systems that enable data migration from a source logical volume to a target logical volume in signal communication with the source logical volume with minimal disruption to the accessibility of that data. The coherency of data on the source logical volume and the target logical volume is confirmed. As part of the migration operation, a pseudoname is remapped from a source logical volume identifier to a target logical volume identifier, enabling application access to continue and avoiding any stopping or reconfiguring of applications accessing the stored data.